Aircraft control system



July 27, 1948. H. WELLS 2,446,149

AIRCRAFT CONTROL SYSTEM Filed June 18, l947 2 Sheets-Sheet 2 Ham/d E. Wells ATTORNEYS.

INVENTOR.

Patented July 27, 1948 AIRCRAFT CONTROL SYSTEM Harold E. Wells, Kenmore, N. Y., assignor. to Bell Aircraft Corporation, Wheatfield, N. Y.

. Application June 18, 1947, Serial No. 755,396

Claims.

1 This invention relates to aircraft, and more particularly to improvements in aircraft flight and taxiing Control means embodying, in combi nation, passenger-pilot control and remote pilot control and, emergency control mechanisms.

One of the objects of the present invention is to provide an aircraft unitary control system of improved form whereby an aircraft may be primarily controlled by either passenger-pilot actuated or remote pilot actuated means; and whereby upon misfunctioning of either of the primary control phases of the system, control of the aircraft may be taken over by meansof an emergency over-control phase of the system.

Another object of the invention is to provide in aircraft control systems improved control power boosting means, whereby relatively lowpower control impulses are automatically boosted in improved manner to relatively high-power impulses so as to insure eifective aircraft control.

Another object of the invention is to provide an improved aircraft control system as aforesaid, which incorporates novel hydraulic power boost control mechanisms.

Other objects and advantages of theinvention will appear in the specification hereinafter.

In the drawing Fig. lis a fragmentary, schematic illustration of a typical applicationof the invention to the landing wheel brakeelements of an airplane, arranged for differential applications of braking effects on wheels at opposite sides of the airplane for ground steering control purposes.

Fig, 2 is a plan view, on an enlarged scale, of a hydraulic power boost mechanism of the control system;

' Fig. 3 is a section taken along line III-III of Fig. 2; and

Fig. 4 is a fragmentary section along line IV-IV of Fig. 3. H

Whereas the drawings illustrate application of the invention only to the ground wheel brake.

control devices on an airplane, itis tube under-- stood that the power output impulses of the control system of the invention may be with equal facility transmitted to the aileron or flap or ele-.

vator or rudder or engine control elements in an airplane; or to adjustable shutter or other accessory devices thereon. avoid undue complexity and duplication of de-. scription in the specification hereinafter, the drawings and the detailed description thereof is limited herein by way of exemplification of the invention to a specific application thereof to an.

aircraft landingwheel braking installation.

However, in order to,

2 a In Fig. 1 of the drawing the airplane landing wheel brake control system is illustratedto include a pair of power applying cylinder-piston units adapted to be connected tothe brake api,

plying mechanisms of corresponding landing wheels located at opposite sides of the airplane; the cylinder-piston units being designated in the drawing at It! and I12. A passenger-pilot brake control arrangement is illustrated as being provided in the form of a pair of hydraulic control valves designated I4IB; the plunger devices I'll-l9 of whichareadapted to be connected to corresponding pedal devices mounted in the air-; craft pilot compartment. It is arranged, that selective pilot-actuation of the connected pedal de-.

vices will result in corresponding applications of;

braking forces through the cyilnder-piston units Ill-l2, and to this end. the pressured fluidintake port of the valve I4 is connected to. a conduit which leads as indicated at 2| into connection with the output port of the pressured fluid supply pump of the system. The pressured fluid intake port of the pedal valve i6 is similarly connected into the pump output line by means of interconnecting conduits 22-524; and preferably, a pres-9 sure accumulator 26 is connected into the line of the conduit!!! to assist in maintaining substan: tially uniform pressures in the system.

The pressured fluid outlet port of the valve I4 is I connected through means of conduits] 28 49-48 into open communication with the pressured fluid intake port of the brake cylinder I2, while the pressured fluid outlet port of the valve I6 is connected through means of conduits 32-43 into a open communication with the pressured fluid intake port of thebrake cylinder It]. It will be un+ derstood that the plunger devices Ill-l9 of the valves |4--l6 are of the longitudinally displaceable type, whereby to control passage of pressured fluid through the cores of the valves from them-.- take to the outlet ports thereof andthat, as is customary in the hydraulic valve control art,[the fluid drainage ports of the valves I l-l6 will be. connected by means of conduits 36-31, respec tively, into the main fluid reservoir 38 of, the system. Thus, it will :be appreciated that the valve plungers l8-l9 are arranged so as to be selectively actuated in response to pedal operations by the airplane passenger-pilot, whereupon corresponding operations ofthe brake control cylinders Ill-l2 will be efiectuated; and that the brakes, at opposite wheels of the airplane may be 7 either simultaneously and equally applied for straight line braking effects, or differentially'ap;

plied for taxiing steering control.

To provide for remote control operation of the airplane, as through means of radio impulse sending apparatus located in another airplane or in a sea vessel or at a ground station; the controlled airplane system is illustrated in Fig. 1 to include a pair of radio receivers designated 4B 42. It will be understood that these receivers 4ll42 may be of any suitable type such as are adapted to receive radio rim-pulses. from corresponding radio sending sets carriedbythe motherairplan or other controlling station and to convert said signals into amplified current impulses; the receivers 40-42 and their corresponding sending sets being difi'erently tuned so as to be independentlyop erable. I

The receiver 40 is illustrated tor-be in electrical connection through suitable conductors with a servo-motor 44; the armature of the motor 44 being geared to a rack bar 46 which operates through lever 41 to displace a positioner or con trol. element 48. of a hydraulic power boost unit whichfis designated generally 9,1550; The radio receiver '42- is likewise electrically connected to a motor lirwhich is similarly geared to a rack 54' and throughlever 56'to another'positioner 58 embodied in another portion of the mechanism withinithepower boost unit'casi-ng 50.

Asfiiliustrated finFigsJ 17-2, the-power boost device 'i's'inthe form of a'dual unit embodying within asingle casing apair'ofindependent power boost mechanisms; one of'th'e mechanisms being controlled"by the'positioner" 48', and the other of the mechanisms being controlled by the positioner'it. i'l ig'. 3 is ags'ectionalview take'napprox imaltiely along line 'III'.-H'I"'of Fig; 2 to "illustrate the' power boost mechanismassociated with'the positioneri iflfand -it i'sito 'be understood that another similar mechanism "is also incorporated Within the lower part of the casing5fl in asso-- ciation withthepositioner5 8 "As shown in'Fig'; 3, the positioner 48 comprises a cylindrical plunger which accurately fits in lonitudinally"slidablelrelation within a reduced bore D6i'tio'i'i"62 .of a tubular-like piston 64. "'Theipist'o'nf' 64fin turn, accuratelyLfit's) in longitudinally slidable' relationwithin a suitably bored portion 65fof"the casing 50'. "Pressure sealing rings are preferably:carried by the piston as indicated. at B6, and also sealing'rings 'willvbe preferably carried byjthe'.v plunger 48. as indicated at"68;,whereby the relatively movable plunger and piston and casingisurfaces will .b e sealed against leakages; The piston 64 is annular-1y Vgrooved, to, provide therearound ajfluid chamberfllladja'cent one end ofj'thelpiston; asecondfluid chamber 12 adjacent theotherf end bffthje piston;.and a 'thi'rdfiuid chamber. 14 intermediately 'ofr'the ends of the piston; IThe casingJMJis provided at the right-hand end of its [bored portion with a reduced bore,

thus providing a,shou1der 16 which fits" the ire-i ducled'pistonfs'urface 64and is adapted to receive theannularffiangeportion' 18 'ofthe piston (between the'johambers 12-14) in, abutting relation th'ereagainst whenever the. piston is displaced to therightfrom the position thereof shown in Fig; 3'; thereby limiting the extent oildisplac'ement'of the piston to the right relative toLthe casing to prevent. "unintended disassembly of the mechanism. annular gland 89' is bolted to;the op posite end'of the .casingifi. to limitdisplacement offtheipiston" 64 toward the left, asviewed inFig. 3;" and the shoulder'i'l'o" is preferably pressuresealed. relative to the piston. as at" 82-; while the gIandfBD' is pressure-sealed relative to the "casing 50-and"to theplunger -4' by means of devices :.indicated at 94 to provide for connection thereat with the threaded end of the conduit 22 bringing fluid underpressure into the valve device A pas- .sagewayqleadsifrom-the bore 94 through the cas- .ringfia't'opposite directions therefrom as indicated ing body is at 9696, and thence downwardly as indicated at -91 at'its 'opposite*ends into open communication withhuid chambers Til-1U formed by annularly grooving the pistons 64- -64 (Fig. 2). The passageway 96 is also formed Withran extension leading" into open communication with the change. ber 12 encircling the right hand end'oflthe piston 64;." The terminal of y the passageway '98.,isp1ug'ged by meansoiastud as indicated at 199," The casingiill is also drillediand tapped, astrindicated at'"|"00 to receive in'thre'aded. co otion thereat one end ar conduit jlflz'which n tunij connects into an on return conduit 104 leading back to the reservoir 38 (Fig.1 1) The valvecasformed interiorlythereof, with pas-y sageways 15-1305 leading. in. oppositeldirections from open: communication with "the. bore, til ll Sand gorresponding chambers 14, encircling the pistons "The tubular pistons 64. are each .formed with bored as'ind'icated at IZI to, 'intercommunicate the leit'hand end of thebor T20 withhafiuid chamber' IZZfformed by annularly rooving-the plungera48. The piston E lisiorn edtwith longn tudinallyjdirected passageways -ll24 ..('Eigs. 7 3: 4) hand end of the piston vand; opening intothe piston boreat, point I25 The leading from the left plunger 48, is 'annularlyj grooved as indicated at and the fluidchamb ers l.26.l.0t.are arrangednin connecting communication by passage ays I 30,. drilled through the. piston 64 so as'to avoid interferences with the passageways;

I24 therein.

Thus, each'valve device of the unit ill isg ar: ranged so'that starting from, .anflinactiye. position asshown inFig; 3; if theplu ger .48v be displaced: for example toward the rightby operation or one of the associated radio-motor .units. 49 44, (Fig. 1) the annular grooved portion of the plunger 4235 will betthereby moved seas-to interconnect.'thepassageways and the passageways I24, Thus, LtheLfluid under pressure from the port 94wil1be permittedtopass through the passageways J i96+10 ll 3il.--le26 l 24 I andchamber 3132 {which is-behind' the piston 64. The action lot. the fluid pressure forces against the. left 1 hand end} of the piston-B4 thence into-the-fluid thence downwardly attheinopposite endsas indi cated at 'Ii06.into open communication' 'wit h the adjacentuits' righthand-end means (oflateral 26linthe surface.

willthen force the latter to move toward the right, thereby applying the fluid pressure forces of the system to operate the primary control valve devices of thesystem, as will be explained hereinafter. Incidental to pilot displacement of the plunger 46 toward the right as viewed in Fig. 3 and prior to responsive movement of the piston 6l as explained hereinabove, the fluid within the chamber I I0 may escape through the passageways II-8- -1-4I66-'I05 and thence through the port I60 into the return line of the system.

It is a particular feature of the valve device of the invention that although the pilot-actuated plunger is movable within the piston 64 in response to applications of only very small operating forces thereon, the plunger at all times senses the fluid pressure forces of the return conduit system, and thereforezgives the pilot device an appropriate feel of the control system. To procure later reverse direction movement of the pis ton 64, the plunger 48 is pilot-displaced toward the left, whereupon communication between the w inlet port .94 and the passageways I24 and the chamber I26 will be severed, while the passageway I22 will be brought into communication \vithtthe passageways I24 so as to interconnect the later with the outlet port I60 through the passageways I2Il-I I8-14-IM. At the same time, the press sured inlet fluid passageway 68 will be conducting pressured fluid in'tothe chamber 12 encircling the right hand end of the piston 64 so as to press against the abutment 16 of the piston thereby, biasingthe latter toward the left relative to the casing. I t

It will be understood of course that the fluid pressures of the system and the relative areas of the pressure-responsive endportions of the piston and the plunger will be so selected and dimensioned as to provide the desired differential operation so that when the plunger is displaced to the right the Ifiilld. pressures behind the left end of the piston will readily overcome the fluid pressures applying against theshoulder 1B of the piston so that the piston will move to the right; and that when the plunger is displaced to the left the fluid pressures againstv the shoulders 18 will provide a corresponding actuation of the piston toward the left. 7

The piston 64 is arranged, as shown in Figs. 2-3, to move forcibly to the right so as to press against the movable element of a control valve device, as will be explained hereinafter; and as illustrated in Figs. 2-3, the piston 64 may include an adjustable push head I52 which is in the form of a stud screwed into the plug H2 and locked thereonby means of a nut I54 for adjustable contact with the movable element of I the valve to be actuated. Thus, it will be appreciated that theboost valve unit 50 embodies a pair of boost valve devices having actuator plungers l'85fi, respectively, and

corresponding bias-heads I'52--I'55 which are arranged as illustrated in Fig. l to actuate springbias-ed movable elements of corresponding control valve devices I56-I'58.

The control valves I56-I58 are of the pressure-throttling type, and the pressured fluid inlet ports thereof connect respectively through conduits I60--'I62 into the pressure supply conduit 22. The controlled fluid pressure outlet port of the valve I56 is connected through a conduit I64 into-the pressure supply conduit 29 Of the brake unit I2, and the controlled pressure outlet port of the valve I58 is connected through a conduit I66 to the pressure supply conduit '34 of the brake unit III. The fluid return ports of the valves 6 I56I5'8 are connected through conduits Hill-I69, respectively, into the return conduit IIll leading to the reservoir of the system. Thus, it is appreciated that upon operation of theradiomotor unit IIl4'4 the control valve I56 will be actuated so as to apply the wheel brake I2; and upon operation of the radio-motorunit lI2--52 the control valve I56 will be actuated to cause the brake unit I6 to operate. I

For emergency control purposes the aircraft control system includes, as shown in the drawing for example, means for permitting the aircraft brakes to be set in case of misfunctioning of either the passenger-pilot or remote controlled phases of the system, such as might occur as a result of gun flre damage to the conduits previously de: scribed. For this purpose in Fig. 1 of the drawing an emergency brake control system is illustrated to comprise a pair of air lines or conduits I10-I 12 leading respectively from connections: to the brake cylinders IIII2 into a common connection with an air pressure control valve I15. The valve I15 is in series with a conduit I16 which connects into a compressed air reservoir or bottle I18, whereby upon opening of the valve I15 the pressure within the bottle I16 will be released against the air in the conduits I11Il-I1i2 to cause the latter to pneumatically operate the cylinder-piston units Ill-I2 for setting the airplane brakes. Preferably, an air pressure gauge I19 will be arranged in connection with the compressed air bottle to keep thepassenger-pilot informed as to the pressure on the system.

It is contemplated that the control valve I15 will be arranged to be operated manually by the passenger-pilot such as by means of any suitable mechanical connection to a conveniently positioned pilot control device. Also, it is contemplated that the control valve I15 will be ar ranged to be actuated from a remote control station, such as referred to hereinabove; and

therefore it will be understood that a suitable radioreceiver (not. shown) may be connected to the valve I15, such as has been explained hereinabove in connection with the radio actuated remote control system. Thus, in event of failure of either of the primary control systems, the emergency valve I15may be actuated either from within the airplane or from the ground to cause the aircraft brakes to be applied.

To provide for actuation of the brake unit l0 either by operation of the pedal valve I6 or the remotely controlled valve I58, alternatively, a shuttle valve I is provided at the point of juncture between the conduits 32-33-I66; and a similar shuttle valve I82 is provided at the juncture of the conduits 3334-I1IJ. A suitable type shuttle valve I84 is provided at the juncture. of,

the conduits 28-2 9 ,-I64, and a similar shuttle valve I86 is provided at the juncture of the conduits 29-3Il--I12. The shuttle valve devices I8II- -I82-I84-I86 may be of the type disclosed:

in my co-pending U. S. patent application Serial No. 751,825, filed June 2, 1947 or in lieu thereof, may be of any other suitable form such as to be adapted to respond to pressure differences within the incoming conduits so as to automatically connect the brake units with the conduits under thehighest fluid pressures. 1

For example, the shuttle valve devices may comprise longitudinally displaceable piston members which are normally biased by spring means or the like in one direction, so as to intercom- ..municate the corresponding brake inlet conduit with the pedal valve conduits 2832; but in 7 eventt'liat the pedal valveconduits' or other" con nested operatingelements become disabled as by g urrfli-e or the like so that t'he fluid pressures fall Within the conduits 28 32 'then' immediately uponoperation of the boostvalve'unitfiil, as ex plained hereinabove, the shuttle-Valves Hill-484 Will-operate automatically-to interconnect the brak'e units -42 F with "the control valves I58-l56. Furthermore, in event" that the radiomotorboost control valve system and/on the conduits leading Y therefrom become disabled as by gun fire or the like, then upon operation of the compressed air controlvalv'e N5 the shuttle valve devices -i-82l'36 will operate automatically to disconnect the damaged portions ofthe control system from the brake units Whilejconnec'ting the compressed air supply conduits INF-I72; into communication with the brake units l0--l2, thereby'eausing the brakes to ibcapplied.

"Iclairn: i IuInanaircraft, a'hydraulic actuation 'clevice, a hydraulic pressure supply, a first conduit leading from said supply to said actuation device, apassenger-pilot operable control device in theline of said "conduit, a second conduit lead: ing froin'said supply to said'actuation' device, a reriiote=pilot operable control device'in theiine o'fisaid second conduit; asecond pressure supply, a-thirdconduit leading irorn said second pressuresupply to'said actuation device, a pilot op- (arable control element in the'line of said third conduit an' d shuttle'valverneans at the junctures of said first and second'and third conduits with said actuation device, said shuttle valve means beingautomatically operable in response to pressurediifferences Within said conduits to selectively communicate only the c'onduit'which is under the highest fluid pressure with said actuation device underall operating conditions,

2111; an aircraft, an aircraft hydraulic actuation device, a hydraulic pressure supply, a first conduit leading from said supply to said actuation device, a passenger-pilot operable control device in the line of said conduit, a second conduit' leading from said supply'to said actuation device, a remote pilotpperable' control element inthe lineof saidsecond conduit, a second pressuresupply, a third conduit leading from said second "pressure supply to said actuation device, apilot operablecontrol, element in the line of said" third "conduit," and shuttle valve means at the junctures of said first and second'and third conduits with said actuation device, said shuttle valv''meansbeing automatically, operable in re s'ponse to pressure difierences Within said con duits to selectively communicate only the. conduit whichis under the highest pressure with said actuation device under all operating cor ditions,

said"-"remote'pi1ot control element comprising a radio impulse receiver-amplifiena servo-motor operable by the output o f'said radio amplifier, and" a pilot-actuated hydraulic valve device coupled to said motor for pilot-actuation thereof, said Valve" device being in the line of said second conduitto controlpressure forces transmitted therethrough to said actuation device.

' 3: In an aircraft, a hydraulic actuation device, a-nrst hydraulic pressure supply, a first conduit leading frorn said first supply to said actuation. device; a passenger-pilot operablecontrol device in 'thelin'e of said first conduit; a second conduit readies from said first supply-to -said actuation device, 'a' reinotepilot operable control device the line-of said second conduit, a second pressure supply, a third 'conduit leading from said pressure supply to said actuation devicaap lot operable control element in'the line of said'third conduit, and'shuttle valve means inth'e lines of said conduitsgsaid shuttle valve-means lc'eir'ig operable automatically in response to pressure differences within said conduits to communicate the conduit which 'is under the highest fluid pressure With'said actuation device and to cldse bfi the others of said conduits.

' 4. In an aircraft, an aircraft hydraulic actuation device, a hydraulic"pres'suresupply, a nrst conduit leading from said-supply to said-actuation device, a passenger-pilotoperablecontrol device in the line o f'sai'd conduit, a; second condiiit leading from said supply to said actuatis device, a remote pilot operable control element in the line Ofsaid second conduit, andsh'uttle-valve means at; the junctures of said first 'and seco'rid conduits with said actuation device;saidsh valve :means being automatically operable 1 sponse to pressure differences Within saidcon duits toselectively communicate only the vcondu-it which is und r the highest pressure was s "d actuation device under all operating conditions; said remote-pilot 'controI element comprisinga radio impulse receiver-amplifier nd as ei-vomotor operable by the" output 2 of saidradio amps; fier and a pilot-"actuated hydraulic valve-device said valve device being in the line of conduit to: control pressure "forces therethrough to said actuationdevice.

5. In' an aircraft, an aincraft' hydra'ulic actuation device, a hydraulicpressur'e supply, afirs't conduit leading from said supply 'to'said-actuation device, a' passenger pilo't operable control device in the line of "said conduit, asecond 'conduit leadingfrom said supply to 'said actuation device, a remote-pil'otoperable control element in the "line of said second conduit, and 'shuttlevalve means at the junctures ofsaid first and-second conduits with said "actuation: d'evice, said-shuttle valve means being automatically- Opel-"able in re sponse to pressure differences withinsaid conduits to selectively communicate only'the conduit which is under the highest-pressure witli s aid' actuation device under all operating conditions, said remote-pilot control element comprising an impulse receiver-amplifier; a "servo-motor oper-' able by the output of saidarrip1ifier,-and= a draulic valve'device couple'd -to-said motor or actuation thereof, said "valve device'being in th'e line of said second ficonduit 'to' controlpres'suife forces transmitted therethrough'tosaid'actuation device. l

said second HAROLD" Biz-WELLS; REFERENCES CITED The following "references 'arei'of record'iri'the file of this patent;

UNITED Y STAZDES PATENTS Number I Name Date $186,235 Brown c Jail; 9, 19 101 2,349,804 Sorensen "May 3'0,"'19 {l4* 2396,9224 'Brodston 'et al -J-M'ar. 195.19% 2,411,705 Benjamin NOV. 26, 1946 transmitted 

